[TorpX]

Welcome aboard, goodpoints!

About damage, things like props and engines are modeled, though perhaps not to the level of detail we might desire. Torpedoes can blow off props, for instance. Engine rooms are modeled in the game, but I can't comment on the finer points. Stock may have more limitations in this area. I mostly play RFB.

I don't think the game models crew realistically, meaning you may have to blast the engine room to pieces, before stopping a ship, maiming/killing the crew may not do it. Not sure they are modeled at all, really.

The graphical effects you mention, holes and such, have nothing to do with the damage inflicted. Ships can be sunk without making any visible holes. It is purely eye-candy. Another factor to consider: AI target ships have some repair ability, but I have no idea how this works, or what limitations it has.

Machine-guns and light AA will have an effect, depending on the armor rating of the target and shell. However, you should keep in mind, that in real-life it could take hundreds of medium sized shells to sink a merchant. Don't expect too much from your deck armament.

In RFB, one generally must damage more than one compartment, so the target sinks by flooding. Sometimes this is a slow and tedious process.